Three flavors of Stage E in one PR:
- **Fence** — fully auto-derived. Adds `kind: 'boolean'` to ParamField
(rendered as ToggleControl), wires `showInfill` through
`def.parametrics`. Legacy `FencePanel` deleted; the auto-derived
`<ParametricInspector>` now drives fence editing entirely.
- **Slab / Ceiling** — kind-owned via `parametrics.customPanel`. The
legacy panels have shape-specific bits (elevation/height presets,
area display, holes list with auto-vs-manual provenance) that don't
fit the auto-derived field model yet. `<ParametricInspector>` learns
to lazy-load and mount `parametrics.customPanel` when present;
legacy `SlabPanel` + `CeilingPanel` files relocate to
`nodes/src/<kind>/panel.tsx` and the legacy copies delete.
When `list` / `computed` / `action` field kinds eventually graduate
to auto-derived support, these custom panels collapse back into
`parametrics.groups`. The plan calls this out under "Custom-behavior
escape hatch" and Foot-gun 5 of the recipe.
Public-surface additions in `@pascal-app/editor`:
- `ActionButton`, `ActionGroup`, `PanelSection`, `SegmentedControl`,
`ToggleControl`, `PanelWrapper` — needed by the kind-owned panels.
Per-kind progress table: fence/slab/ceiling all flip to E ✅.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
